Method and device for measuring the temperature of material in a rotatory furnace

ABSTRACT

A small portion of the hot material in a rotatory furnace is poured out through an opening in the furnace wall during a period of the rotation into a measuring vessel and the temperature of the material is measured before any substantial cooling of the material has time to occur. Transversely under the rotatory furnace are guiding rails movable between two positions. Connected to a stand on a base attached to the furnace is a device for opening and closing the furnace wall opening, and an upwardly open measuring vessel movable along the guides back and forth. In the measuring vessel are a thermocouple, an engaging dog attached to the furnace to displace the measuring vessel in synchronism with the furnace wall opening, and means for emptying the vessel before a new collection takes place.

United States Patent Myreen [151 3,675,467 451 July 11, 1972 [54] METHODAND DEVICE FOR MEASURING THE TEMPERATURE OF MATERIAL IN A ROTATORYFURNACE 211 Appl. No.: 40,812

[30] Foreign Application Priority Data June 3, 1969 Finland [663/69 [52][1.5. CI ..73/35I, 73/354, 73/42l B [5!] lnt.Cl ..GOIk I/I4,G0lkl3/l2[58] Fleldofsearch ..73/35l,354,42l B,DIG.9

[56] References Cited UNITED STATES PATENTS 3.613.453 l0/l97l Small etal. ..73/35l 1379.062 4/l968 Lellep ..73/35l 3,025,705 3/1962 Blake etal. l 36/229 X R26,409 6/1968 Hance ..73/359 FOREIGN PATENFS ORAPPLICATIONS l,l09.5l2 4/1968 Great Britain ..73/35l PrimaryExaminer-Louis R. Prince Assistant Examiner-Frederick ShoonArromey-Ralph E. Bucknam, 1cm D. Reingold. Robert R. Strack and Henry A.Marzullo, Jr.

[ ABSTRACT A small portion of the hot material in a rotatory furnace ispoured out through an opening in the furnace wall during a period of therotation into a measuring vessel and the temperature of the material ismeasured before any substantial cooling of the material has time tooccur.

Transversely under the rotatory furnace are guiding rails movablebetween two positions. Connected to a stand on a base attached to thefurnace is a device for opening and closing the furnace wall opening,and an upwardly open measuring vesel movable along the guides back andforth. In the measuring vessel are a thermocouple, an engaging dogattached to the furnace to displace the measuring vesel in synchmnismwith the furnace wall opening, and means for emptying the vessel beforea new collection takes place.

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METHOD AND DEVICE FOR MEASURING THE TEMPERATURE OF MATERIAL IN AROTATORY FURNACE BACKGROUND OF THE INVENTION 1 Field of the InventionThe invention relates to the field of measuring the temperature of thematerial in a rotatory furnace, specifically to a device for measuringthe temperature and to a method for measuring the temperature of thematerial in a rotatory furnace.

2. Prior Art One of the most essential prerequisites for efficientcontrol of a cement oven is the achievement of significant process datawhen the furnace is out of balance and this is true both with manualcontrol as well as when analog or digital control circuits are employed.In order that such process data might be obtained, the oven must beprovided with reliable measuring instruments. So far, no one has beenable successfully to instrument the calcinating zone in cement furnaces.Especially in long wet ovens, in which the material has a tendency to befed forward by jerks, it is essential to obtain information from thissection of the oven.

In order to measure the temperature in the calcinating zone, up to datethermocouples installed in the furnace have been used for measuringeither the gas or the material temperature, the thermoelectric E.M.F.being read after its conduction over slip rings. However, sturdyprotective sockets are invariably necessary to protect the thermocouplesso that these may resist the serious action of wear. However, thesedevices impart to the measuring system such high thermal capacity thatthe material temperature has no time to reach its proper value beforethe thermometer pocket becomes separated from the bed of material andonce more it is heated by the hot gases which flush it. Even if a pocketis constructed in the inner masonry of the furnace and the thermocoupleis placed in it, whereby it is embedded in material through one halfrevolution of the furnace, there is not enough time for the thermocoupletogether with its socket to acquire the true temperature of thematerial. The risk is also present that the pocket is not emptied of thematerial contained in it, and the thermocouple becomes isolated from thematerial and consequently inoperative.

Attempts have also been made to measure the gas temperature in thecalcination zone of a cement furnace, but apart from the fact that thegas temperature is of far lesser interest than the material temperature,the measurement is also accompanied by great technical difficulties sothat the results of measurement may display very great deviations fromthe actual values.

SUMMARY OF THE INVENTION According to the invention a small portion ofthe hot material is poured out through an opening in the furnace wallduring a certain period of the rotation of the furnace which naturallyis less than half a period. The discharged material is collected and thetemperature thereof is measured before any substantial cooling of thematerial takes place.

The object of the present invention is therefore to provide a method formeasuring the material temperature in a rotating oven, in particular inthe calcinating zone of a cement furnace, which method is free of thedrawbacks and faults which have been connected with the methods of priorart already men tioned.

The invention also relates to a device for carrying out the methodaccording to the invention, this device having an open measuring vesselwith inserted thermocouple and which has been arranged for a desiredperiod during one rotation of the furnace to be carried from a restposition to in collecting position under a hole in the oven wall, and adevice for automatically opening and closing said hole in the oven wallsynchronously with the movement of the measuring vessel. Thethermocouple is suitably openly placed in the thermally insulatedmeasuring vessel, whereby it has low thermal capacity and is ablerapidly to assume the prevailing temperature.

The method and the device according to the present invention possess anumber of advantages over previously employed methods and apparatuses.First, one measures the true tern perature of the material because,since the measurement takes place outside the furnace, the hot gases inthe oven cannot influence the result of measurement and since thethermocouple has no protective pocket, its thermal capacity is low,whereby the thermocouple is rapidly heated to the temperature of thematerial before conduction of heat from the measuring vessel to itsenvironment has had time to affect the results of measurement.Furthermore, it is easy to supervise the operation of the measuringdevice because no parts of the equipment are located inside the ovenwhere they are not under inspection. No vital parts rotate along withthe oven, and they may therefore be removed from service for repairs atany time without detriment to the operation of the oven. Since thetemperature measurement is carried out outside the oven, no slip ringtransfer of the measuring signal is necessary; a simple millivoltmetermay therefore be used as the instrument indicating and recording thematerial temperature. This is a great ad vantage especially if themeasuring signal has been incorporated in an automatic control circuit,because the slip ring trouble, which is rather highly common in factoryconditions, is completely eliminated. Finally, the measuring vesselsimultaneously operates as the sampling vessel for oven material, e.g.for purposes of chemical analysis.

The quantities of material removed from the furnace at measurement arenegligible, and they may be returned to the oven if desired, e.g.immediately after the measurement or intermittently together withrecirculated dust or together feeding the furnace. It is not necessaryeither, at normal operation, to perform continuous measurements; thematerial quantities removed can be reduced in this way, as can also thewear of the measuring equipment.

It is an apparent drawback of the method according to the invention thatthe measuring pulse is not continuous and that it is instead obtained inthe form of discrete values with certain intervals depending on therotation of the oven and on the time constant of the measuring vessel.It is entirely possible, however, to maintain a measuring frequencywhich is normally considerably above the oscillation frequency ofprocess disturbances, and consequently it lacks practical significance.

DESCRIPTION OF THE DRAWINGS In the drawing,

FIG. I shows a cross section of a rotating oven and a total view of ameasuring device according to the invention, while FIG. 2 shows ameasuring vessel belonging to the device,

FIG. 3 shows a front-view ofa plug with the lever arm, and

FIG. 4 shows a similar plug from the side.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. I reference numeral Iindicates a rotating oven. In its mantle numeral 2 designates an openingwhich is in the closed position. Plug 3 is capable of opening. The plughas been mounted on a lever 4 tumable around 5, another lever arm 6,which forms a substantially right angle with lever arm 4, being rigidlyconnected with the latters turning axis. The plug 3 is normally kept inclosed position by spring action.

For the purpose of opening the plug, an opening rail 7, which isconcentric with the outer mantle of the oven, has been mounted in suchposition under the oven I that in the course of rotation of the oventhis rail is hit by the lever arm 6. The arm is thereby turned,resulting in an outward swing of the plug 3, the length of the raildetermining the opening time. The rail 7 is appropriately provided witha portion 8 causing a first, brief opening of the plug 3, the joltcaused by closure of the plug being intended to remove potentialdeposits which might plug the opening 2, before the plug is once moreopened by action of the rail 7 for sampling of material. The rail 7 iscarried by arms 9, which are tumably carried at 10 in a stand I1 so thatwith the aid of a power cylinder (not depicted) the rail can be turnedto one side around 10 into inactive position, in which it is notcontacted by the lever arm 6.

For collecting the material which runs out through the opening 2 in thecourse of the ovens rotation, a vessel 12 has been provided, whichsimultaneously acts as measuring vessel and for this purpose it isprovided with an exposed temperature sensor 13 (FIG. 2); this sensor maybe, for instance, a nickel vs. chromenicltel thermocouple connected by aflexible lead to an indicating instrument (not depicted). The collectingand measuring vessel 12 has preferably the shape of a frustoconicalcone, with a wider top than bottom in order to facilitate emptying, andin the embodiment shown in FIG. 2, it is provided with a flatter conicalcollar 14 around its mouth and with a thermally insulating jacket 15.The measuring vessel 12 is mounted in a holder 16, which is tumablycarried in a carriage 17. The carriage 17 has been arranged to run onrolls along guides 18 consisting of U-beams turned to face each other.The guides 18 shaped so as to run in their principal part concentricallywith the outer mantle of the oven 1, and they turnably pivoted at 19 tothe stand 11 and can be moved, by means of a power cylinder 20 connectedto the free end of the guides, between the collecting position, shown inthe figure, and a lower emptying position.

When the guides 18 are in the position shown in the figure, with thevessel 12 close to their free end, the plug 3 which has been placed inits opened position acts as engaging dog and takes the vessel 12 along,with the result that during the time material runs out through theopening 2, the vessel is in collecting position under the opening. Whenthe measuring vessel has arrived at the upper end position, it engageswith a locking device 21, which fixes the measuring vessel so that itremains stationary in said position for the period in which thetemperature measurement is accomplished, e.g. for three full revolutionsof the oven. The opening rail 7 is kept turned into its inactiveposition during this period. The guides 18 are then lowered to theirlower position, whereby the carriage 17 of the measuring vessel rollsdown to the extreme end of the guides. This causes the measuring vessel12 to strike against stop 22, whereby it is tipped upside down and thecontents run down into a chute 2.3 to be recovered. Stop 22 serves thefunction of causing the measuring vessel 12 to be emptied. The openingrail 7 is then turned back into operating position and the guides 18 areraised into collecting position for another measuring cycle.

Control of the moving parts in the system can be easily automated byconventional means so that the device will carry out consecutivemeasuring cycles at desired intervals, but it is obviously equallypossible to provide for such control that the equipment is started byhand for performing only one measuring cycle, every time the result ofmeasurement is desired.

What is claimed is:

l. A method of measuring the temperature of material in a rotatoryfurnace operated at elevated temperature, at intervals comprising:

first pouring a small portion of the hot material out through an openingin the furnace wall during a period of the rotation of the furnace;

moving a separate measuring vessel together with the furnace wall duringsaid period of rotation of the furnace; collecting the dischargedmaterial in said separate measur- 4 ing vessel; and

then measuring the temperature of the collected material in the vesselbefore any substantial cooling of the material has time to occur.

2. A device for measuring the temperature of material in a rotatoryfurnace operating at elevated temperature, comprising:

a. a base;

b. a stand on the base;

or first and second guiding means attached to the stand transverselybeneath the fumace;

d. a device attached to the furnace for opening and closing an openingin the furnace wall and guided by the first guiding means;

e. an upwards open measuring vessel movable along the second guidingmeans from a rest position to a collecting position under the furnacewall opening for the duration of a desired period during one revolutionof the furnace;

f. a temperature sensing element in the measuring vessel;

g. means on the stand for emptying the measuring vessel after thetemperature of the collected hot material has been measured by thetemperature sensing element; and

h, means on the furnace for moving the measuring vessel along saidsecond guiding means in synchronism with the flu-nace wall opening.

3. A device as recited in claim 2, in which the temperature sensingelement comprises an exposed thermocouple placed in the measuring vesselto be in direct contact with the collected material.

4. A device as recited in claim 2, in which the device for opening andclosing the furnace wall opening comprises:

a tumably pivoted two-armed bell crank, which is springloaded tomaintain the furnace in a normally closed position; and

a closing plug for opening in the furnace wall mounted on the other armof the bell crank which is arranged in the course of rotation of thefurnace to engage with the guiding means for opening the plug and formaintaining the plug in open position.

5. A device as recited in claim 4, in which the first guiding meanscomprises a guide rail having a short front portion for accomplishing abrief premature opening and closing movement of the plug before this isagain opened for collecting hot material from the furnace.

6v A device as recited claim 5, which comprises means for moving theguide rail into an inoperative position out of engagement with the bellcrank lever.

7. A device as recited in claim 4, in which the second guiding means forguiding the measuring vessel are movable between a rest position andcollecting position and the means for moving the measuring vessel insynchronism with the furnace wall opening comprises an engaging dog onthe furnace arranged to displace the measuring vessel along the secondguiding means into position under the opening in collecting position ofthe guiding means.

8. A device as recited in claim 7, in which the engaging dog consists ofthe closing plug in its opened position.

1. A method of measuring the temperature of material in a rotatoryfurnace operated at elevated temperature, at intervals comprising: firstpouring a small portion of the hot material out through an opening inthe furnace wall during a period of the rotation of the furnace; movinga separate measuring vessel together with the furnace wall during saidperiod of rotation of the furnace; collecting the discharged material insaid separate measuring vessel; and then measuring the temperature ofthe collected material in the vessel before any substantial cooling ofthe material has time to occur.
 2. A device for measuring thetemperature of material in a rotatory furnace operating at elevatedtemperature, comprising: a. a base; b. a stand on the base; c. first andsecond guiding means attached to the stand transversely beneath thefurnace; d. a device attached to the furnace for opening and closing anopening in the furnace wall and guided by the first guiding means; e. anupwards open measuring vessel movable along the second guiding meansfrom a rest position to a collecting position under the furnace wallopening for the duration of a desired period during one revolution ofthe furnace; f. a temperature sensing element in the measuring vessel;g. means on the stand for emptying the measuring vessel after thetemperature of the collected hot material has been measured by thetemperature sensing element; and h. means on the furnace for moving themeasuring vessel along said second guiding means in synchronism with thefurnace wall opening.
 3. A device as recited in claim 2, in which thetemperature sensing element comprises an exposed thermocouple placed inthe measuring vessel to be in direct contact with the collectedmaterial.
 4. A device as recited in claim 2, in which the device foropening and closing the furnace wall opening comprises: a turnablypivoted two-armed bell crank, which is springloaded to maintain thefurnace in a normally closed position; and a closing plug for opening inthe furnace wall mounted on the other arm of the bell crank which isarranged in the course of rotation of the furnace to engage with theguiding means for opening the plug and for maintaining the plug in openposition.
 5. A device as recited in claim 4, in which the first guidingmeans comprises a guide rail having a short front portion foraccomplishing a brief premature opening and closing movement of the plugbefore this is again opened for collecting hot material from thefurnace.
 6. A device as recited claim 5, which comprises means formoving the guide rail into an inoperative position out of engagementwith the bell crank lever.
 7. A device as recited in claim 4, in whichthe second guiding means for guiding the measuring vessel are movablebetween a rest position and collecting position and the means for movingthe measuring vessel in synchronism with the furnace wall openingcomprises an engaging dog on the furnace arranged to displace themeasuring vessel along the second guiding means into position under theopening in collecting position of the guiding means.
 8. A device asrecited in claim 7, in which the engaging dog consists of the closingplug in its opened position.